2005 BMW 745i cooling

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Components
Cooling System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
- Coolant Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
- Water Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
- Map-Controlled Thermostat. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
- Cooling Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
- Radiator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
- Expansion Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
- Transmission Oil/Water Heat Exchanger . . . . . . . . . . . . . . . . . . . . . . . . .44
- Electrically-Operated Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
- Viscous Coupling Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Engine block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
- Oil Sump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
- Crankcase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
- Crankshaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
- Connecting Rods and Pistons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
- Flywheel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
- Vibration Damper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Lubrication System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
- Oil Jets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
- Oil Check Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
- Oil Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
- Oil Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
- Pressure Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
- Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Review Questions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

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N62 Engine
N62 ENGINE
Model: E65 - 745i / E66 - 745Li
Engine: N62B44
Production Date: 11/2001 - E65, 01/2002 - E66
Objectives of The Module
After Completing this module, you will be able to:
• Describe the two stage oil supply.
• Distinguish the difference between the left and right drive chain tensioning assem-
blies.
• Explain the Bi-VANOS operation.
• Understand the function of the Variable intake manifold.
• Explain the cooling circuit flow.
• List what chamber A and chamber B is used for in the Bi-VANOS system.
• Identify the Secondary air components.
• Explain how the initial VANOS position is retained when oil pressure is not present.
• List the proper drive belt removal procedure.
• Describe the throttle valve functions.
• Identify the N62B44 designation.

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Due to the high power capacity of 180 A, the alternator is cooled by the engine's cooling
system to enhance heat dissipation. The brushless Bosch alternator is installed in an alu-
minum housing which is mounted to the engine block. The exterior alternator walls are sur-
rounded with circulated engine coolant. The function and design of the alternator is the
same as in the M62, with only minor modifications. The BSD interface (bit-serial data inter-
face) for the ECM is new.
* Further details found in the cooling circuit
section
Regulation
The alternator communicates with the Engine Control Module (ECM) via the BSD (bit-seri-
al data interface). The alternator conveys data such as model and manufacturer. This is
necessary to allow the engine management system to adapt it’s calculations and specific
control to the type of alternator fitted.
17
N62 Engine
42-02-17
Alternator
1. Watertight Housing
2. Rotor
3. Stator
4. Seal
Alternator Coolant Flow
1. Coolant Return Flow
2. Coolant Inlet Flow
42-02-18

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N62 Engine
Cooling System
Coolant Circuit - 14 Liter Coolant Capacity
42-02-56
Cooling System (Circuit Flow)
1. Cylinder Head Bank 5-8 12. Radiator
2. Coolant Supply (heater core) 13. Radiator Partition (low temp section)
3. Water valve with electric water pump 14. Temperature Sensor
4. Cylinder Head Gasket 15. Water Pump
5. Coolant Supply Line 16. Radiator Return Flow
6. Cylinder Head Ventilation Lines 17. Radiator Ventilation Line
7. Hole (crankcase venting system) 18. Expansion Tank
8. Transmission oil lines 19. Thermostat
9. Oil/water heater exchanger for automatic transmission 20. Cylinder Head Bank 1-4
10. Thermostat for transmission oil heat exchanger 21. Vehicle Heater
11. Alternator Housing 22. Radiator (High Temperature Area)

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N62 Engine
Coolant Circuit
The coolant flow has been optimized allowing the engine to warm up as quickly as possi-
ble after a cold start as well as even and sufficient engine cooling while the engine is run-
ning. The cylinder heads are supplied with coolant in a cross-flow pattern. This ensures
more even temperature distribution to all cylinders. The cooling system ventilation has been
improved and is enhanced by using ventilation ports in the cylinder heads and in the radi-
ator. The air in the cooling system accumulates in the expansion tank. When a pressure of
2 bar is reached in the expansion tank, the air is bled out by the pressure relief valve in the
reservoir cap.
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The ventilation ports in the front of the cylinder heads provide quicker “self bleeding”
during a routine coolant exchange. The complex cooling system and the small ventilation
ports require that time should be allowed after the cooling system has been filled for the air
to escape.
Coolant flow in the Engine Block
The coolant flows from the water pump through the feed pipe (1) in the engine's V and to
the rear of the engine block. This area has a cast aluminum cover (see following illustration).
From the rear of the engine, the coolant flows to the external cylinder walls and from there
into the cylinder heads.
The coolant then flows from the cylinder heads into the engine block V and through the
return connection (3) to the thermostat housing. When the coolant is cold it flows from the
thermostat (closed) directly into the water pump and back to the engine (recirculating for
faster warm up).
When the engine reaches operating tempera-
ture (85 ºC-110 ºC), the thermostat opens the
entire cooling circuit to include the radiator.
42-02-57
Engine Block Coolant Flow
1. Coolant from the water pump through the feed pipe
to the rear of the engine.
2. Coolant from the cylinder walls to the thermostat
housing.
3. Return connection to water pump/thermostat.

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N62 Engine
Map-controlled Thermostat
The map-controlled thermostat allows the engine to be cooled relevant to operating con-
ditions. This reduces fuel consumption by approximately 1-6%. The electrical connections,
the design and the map-controlled thermostat response have been enhanced. The map-
controlled thermostat function is the same as previous engines (M62).
Cooling Module
The cooling module contains the following main cooling system components:
• Cooling radiator
• Air conditioning condenser
• Transmission oil/water heat exchanger
• Hydraulic fluid radiator
• Engine oil radiator
• Main electric fan
• Fan shroud for viscous coupling fan
All the components (with the exception of the transmission oil radiator) can be removed for
repairs without disassembling any other coolant circuit. All connections have been fitted
with the quick-release coupling which are used in current models.
Maped-Controlled Thermostat
1. Radiator Return Flow To Thermostat
2. Connection for Thermostat Heating Element
3. Temperature Sensor
4. Radiator in-flow (hot coolant from engine)

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N62 Engine
Cooling Radiator
The radiator is made from aluminum and is divided into a high-temperature section and a
low-temperature section by a partition wall (see coolant circuit diagram). The coolant first
flows into the high-temperature section and then back to the engine, cooled.
Some of the coolant flows through an opening in the radiator partition wall to the low-tem-
perature section where it is cooled further. The coolant then flows from the low-tempera-
ture section (when the ÖWT thermostat is open) into the oil/coolant heat exchanger.
Coolant Expansion Tank
The expansion tank is mounted on the right hand wheel housing (engine compartment).
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The expansion tank should never be filled above the Max marking. Excess coolant is
expelled by the pressure relief valve in the cap as it heats up. Avoid overfilling the expan-
sion tank because the cooling circuit design ensures very good “self bleeding”.
Cooling Components
1. Cooling Radiator 4. Engine oil/air heat exchanger connection
2. Expansion Tank (hot countries only)
3. Water Pump 5. Transmission oil/coolant heat exchanger

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N62 Engine
Transmission Oil/Coolant Heat Exchanger
The transmission oil/coolant heat exchanger ensures that the transmission oil is heated up
quickly and also that it is appropriately cooled. When the engine is cold, the transmission
oil/coolant heat exchanger thermostat switches into the engine's recirculated coolant cir-
cuit. This allows the transmission oil to heat up as quickly as possible (with the engine
coolant).
When the return flow water temperature reaches 82 ºC, the thermostat switches the trans-
mission oil/coolant heat exchanger to the low-temperature coolant radiator circuit (refer to
the cooling circuit diagram) to cool the transmission oil.
Electrically Operated Fan
The electric fan is integrated in the cooling module and is mounted directly in front of the
radiator. The speed is regulated by the ECM.
Viscous Coupling Fan
The viscous coupling fan is driven by the water pump. The noise output and the perfor-
mance of the fan coupling and the fan wheel have been optimized as compared with the
E38M62. The viscous coupling fan is used as the final level of cooling and switches on at
an air temperature of 92 ºC.
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